1. Field of the Invention
The present invention is directed to an impact resistant roofing shingle providing far greater resistance to impact than standard roofing shingles and a process of making same. More specifically, the present invention is directed to an impact resistant roofing shingle providing the highest level of protection against impact damage to roofing shingles and a process of making those shingles.
2. Background of the Prior Art
Losses sustained to building roofs caused by climatic conditions such as hailstones has focused development of roofing shingles having increased impact resistance. This need in the art is particularly acute in those geographic areas which are subject to these climatic conditions. Specifically, such areas as the Plain and Rocky Mountain states are particularly subject to roofing damage caused by hailstorms and the like. Indeed, the insurance laws of the state of Texas provide cash rebates to homeowners insurance policies wherein the insured property's roof employs Class 4 roof covering materials.
The most recognized criteria for impact resistant roof covering materials is provided by Underwriters Laboratory Standard Test UL 2218, which is incorporated by reference. Standard Test UL 2218 categorizes roof covering materials as Class 1, 2, 3 or 4. Class 1 is the category assigned to the least resistant while Class 4 provides the highest recognized impact resistant.
Impact resistant roofing materials are known in the art. For example, U.S. Pat. No. 6,228,785 discloses an asphalt-based roofing material which includes a substrate coated with an asphalt coating in which a surface layer of granules is embedded in its top surface. The bottom surface, covered with an asphalt coating, however, is bonded to a web. The bond between the asphalt coating and the web is effectuated by fusing of the asphalt coating and the web. This is achieved by intermingling, caused by melting, of the web and the asphalt coating.
U.S. Pat. No. 5,571,596 describes an asphalt-coated roofing shingle which includes an upper layer of a directional fiber such as Kevlar fabric, a middle layer of fibrous mat material, such as a glass fiber mat, and a lower layer of a directional fiber such as E-glass fabric. Unlike the teaching of the aforementioned '785 patent, wherein the web, fused to the lower region of the asphalt coating, provides impact resistance, the impact resistance of the roofing shingle of the '596 patent is ascribed to the lower layer of directional fiber.
A third impact resistant roofing shingle is set forth in U.S. Pat. No. 5,822,943. The laminated roofing shingle of the '943 patent includes an upper layer of a scrim bonded, by means of an adhesive, to a lower layer mat. The preferred adhesive of the upper and lower layers is a rubber binder.
In addition to the aforementioned impact resisting roofing material designs, it is well known in the art to modify the asphalt coatings of roofing materials with polymer-type modifiers. Such designs, although effective in theory, have not been very effective in resisting climatic impacts caused by hailstones and the like. On the other hand, modifying the asphalt with polymer-type additives increases the asphalt coating raw material cost. In addition, installation of modified asphalt is more difficult than standard unmodified asphalt coated roofing materials.
The above remarks establish the need in the art for a new type of impact resistant roofing shingle that meets the most stringent impact resistant, e.g. Class 4 as defined in UL 2218, yet is simple in design and easy to manufacture.